by Guest Author, Erin Loury

Thought to be the largest growing inland trout in North America, Lahontan Cutthroat can reach 50 inches and 40 pounds, though stories from mining boom days describe fish reaching 60 pounds. Lahontan Cutthroat Trout have since disappeared from most of their native range in the Great Basin.

While the fish have been re-introduced into Nevada’s Pyramid Lake with the help of hatchery stocking, only two lakes naturally support Lahontan Cutthroat Trout. One of these self-sustaining populations is in Summit Lake, which is managed by the Summit Lake Paiute Tribe. In a new video produced by FISHBIO, William Cowan, the Natural Resource Department Director for the tribe, explains that Lahontan Cutthroat have great significance for his people. The native name of the Paiute people from the Summit Lake area translates to “trout eaters,” and fishing for trout is a special cultural practice.

Given the cultural importance of Lahontan Cutthroat trout, the Summit Lake Paiute Tribe has undertaken a long-term monitoring program to study trends in abundance of the fish at the lake. Lahontan Cutthroat Trout exhibit two forms: a lake form that lives in the lake as adults and spawns in Mahogany Creek, an inflow into the lake; and a stream form that lives in Mahogany Creek year round. The creek is therefore critical habitat for these fish, but prior to the 1990s, widespread cattle grazing damaged the integrity of the stream.

Once the tribe constructed fences to keep cattle out of the creek, trout habitat and numbers improved. The tribe also teamed up with researchers from the University of Nevada, Reno, (UNR) to complete a food web assessment of the lake. The scientists found that Lahontan Cutthroat Trout at Summit Lake are the fattest population of the species in the Great Basin (that is, they have the highest ratio of body mass to length), and feed almost exclusively on benthic amphipods. Graduate students from UNR are currently studying the lake- and stream-resident forms of the trout to understand how these populations interact.

The tribe’s multifaceted fisheries monitoring program employs many different tools, ranging from a fish trap, where tribe biologists weigh and measure the fish by hand, to cutting-edge fish camera technology. A few-meter stretch of Mahogany Creek probably contains one of the highest densities of fisheries monitoring equipment per stream area! A Passive Integrated Transponder (PIT) tag antenna detects and records fish from the lake that have been implanted with PIT tags, which function like microchips used in pets.

All fish, both tagged and untagged, are then recorded by a VAKI Riverwatcher automated infrared fish counter. Fish also pass through the Smolt Spy, a custom-designed piece of automated fisheries monitoring equipment that helps the tribe record video of both adult and juvenile Lahontan Cutthroat Trout migrating in the stream, and also validate the data from the Riverwatcher. In addition to all this detailed fish passage information, the tribe is recording stream flow and weather data, with the hopes of creating an environmental model that can be used to help monitor and manage the Lahontan Cutthroat Trout and other species in the Summit Lake ecosystem as the climate changes. Watch the video to learn more about these stunning fish holding out in a remote and fascinating landscape!